Cities and towns tend to be hotter than surrounding rural areas creating what are called urban heat islands. In a recent study, leaf-cutter ants (Atta sexdens rubropilosa) living in cities were found to have a higher heat tolerance than those living in rural areas (Angilletta et al., PLoS One 2(2): e258). Figure 3 from the article (below) shows urban ants (black lines) tolerating longer exposures to heat (42°C) than ants from rural areas (grey lines).

Researchers are unsure whether this adaptation in ants is a result of genetic differences or environmental factors.